I'm assuming someone strong on maths might be able to explain that if the algorithm is known it might be possible to break it because in a way data is being 'reused', though in an encrypted, compressed form the first time, as the key the second.

If the security does degrade, at what point/how much? (Assuming neither ends have the conversation have been compromised).

edit: thanks for looking guys, I forgot that random data is hard to compress; question answered.

Why do you think OTP is secure/insecure depending on the content of the message Alice wants to send to BoB?
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dfcMar 28 '14 at 0:01

... I'm not sure I follow? I'm aware that repeated pads will throw the entropy off, so I'm open to the concept that transmitting pads (even compressed) might do the same. Is that what you mean?
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pacifistMar 28 '14 at 0:05

2

Since the OTP is supposed to be crytographically secure random data, it should not be compressible at all.
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JohnnyMar 28 '14 at 0:08

Are we assuming the OTP is securely implemented, transferred and used?
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dfcMar 28 '14 at 0:09

It is also worth pointing out that "compression allows you to transmit something larger than the number of bytes used in transmission" is not true for random data. Try dd if=/dev/urandom of=rand bs=1024 count=10000 ; xz -k rand ; du -b rand rand.xz
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dfcMar 28 '14 at 0:14

So if you're using the "remaining," unused part near the end of your one time pad to transmit a new one time pad, you're going to end up with a very small "new" one time pad... and the same problem that you're almost near the end of it.